The present embodiments relate to a method for determining collateral information describing blood flow in collaterals of a blood vessel system of a target region of a patient. The present embodiments also relate to a medical imaging device, a computer program and an electronically readable data medium for determining the collateral information.
The cause of many medical conditions is a critical disturbance of the blood supply. One example is a stroke, where the blood supply to the brain is critically disturbed. In cases of stroke, medical image data is typically recorded as a vascular data set indicative of the blood vessel system enabling an assessment of possible interventions and to issue prognoses for convalescence. Every patient's blood vessel system is individual (e.g., a specific diameter) and may include unique interconnections between individual blood vessels (e.g., anastomoses). Blood vessels of this size are generally referred to as collaterals. Collaterals generally ensure that the blood is supplied to a region of tissue in the event of a displacement or injury to individual blood vessels. If the target region of the patient is the brain (e.g., the condition of the leptomeningeal anastomoses), collaterals have been found to be one of the decisive factors in predicting the outcome of mechanical recanalization.
Typically, four-dimensional angiography vascular data sets are used for evaluations of this kind. In addition to three spatial dimensions, four-dimensional vascular data sets also describe (e.g., in the image values) the temporal flow of a contrast medium and/or marked blood constituents through the target region. A contrast medium is usually used with X-ray imaging. In addition using a contrast medium with magnetic resonance imaging, the use of spin-labeling and comparable techniques is known. Hence, 4D-angiography vascular data sets provide both anatomical and physiological information relating to the blood flow. When vascular data sets are used for clinical purposes (e.g., in the context of stroke treatment), the status of collaterals is extremely important. For example, known methods for the evaluating the status of the collaterals are visual evaluation of two-dimensional images from digital subtraction angiography (DSA) and computed tomography angiography (CTA) with reference to the filling of the respective blood vessels. In these methods, a doctor with the appropriate training performs the analysis manually. As such, it is a disadvantage that evaluation and classification of the severity of the occlusion or flow disturbance for the purposes of an assessment of the therapeutic measures for stroke treatment is subjective.